644400504 has 288 divisors, whose sum is σ = 2147418000. Its totient is φ = 173352960.

The previous prime is 644400469. The next prime is 644400511. The reversal of 644400504 is 405004446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 2813862 + ... + 2814090.

Almost surely, 2^644400504 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644400504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1073709000).

644400504 is an abundant number, since it is smaller than the sum of its proper divisors (1503017496).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644400504 is a wasteful number, since it uses less digits than its factorization.

644400504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 299 (or 281 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 27.

The square root of 644400504 is about 25385.0448886741. The cubic root of 644400504 is about 863.7444910615.

The spelling of 644400504 in words is "six hundred forty-four million, four hundred thousand, five hundred four".